In April 2018 an anonymous collector from New England was poised to become a multimillionaire after a rare gold coin he thought was fake turned out to be the real deal. But the lucky numismatics enthusiast isn't the only collector to have discovered that a supposed copy was actually bona fide. We take a look at some alleged imitations that were eventually declared genuine.

The San Francisco Mint produced just 268 gold $5 Liberty Half Eagle coins back in 1854 and only three were thought to have survived to the present day. A New England collector, who has chosen to remain anonymous, was convinced his coin was a cheap 'tribute', but held out hope it was genuine. The collector had shown the coin to several dealers who told him it was a copy, but turned to the Numismatic Guaranty Corporation (NGC) in Florida as a last resort. Using high-resolution images of the existing coins, the NGC experts were able to confirm its authenticity. 

Expecting to be told the coin was fake, the collector was reportedly stunned by the news it is genuine and worth several million dollars. A sensational find, NGC chairman Mark Salzberg has compared the discovery to stumbling upon a Picasso in a garage sale.

In 2017, Gloucestershire businessman Harry Reid appeared on the BBC's Fake or Fortune? show with a landscape painting he'd bought from TV art expert Philip Mould in 2000 for $46,000 (£35k). In a strange turn of events, the new owner swore that the picture he bought from the art expert was actually by John Constable, but couldn't prove it.

Mould, who co-presents the show, arranged for the artwork to be analysed by experts in Los Angeles. Authenticity technology has advanced significantly since 2000, and the US art sleuths were able to confirm the painting is the genuine article.

In fact, the painting is an early version of Constable's famous masterpiece The Hay Wain, and has been described as an important museum-worthy find by scholars of the Victorian painter. Unfortunately for Mould, the painting he sold for just $47,000 (£36k) 18 years ago is actually worth $2.6 million (£2m).

Lincolnshire collector Justin Whiting chanced upon this grainy photo on eBay in July 2017 and recognised it as a picture of infamous outlaw Jesse James, but was certain the image was a later copy on account of its bargain basement price. But the history buff still snapped it up for just $9.20 (£7).

Whiting sent the photo to Kent Gibson, a Los Angeles-based forensic expert who, after intensive study, declared it the real McCoy. The image was captured between 1861 and 1862 when James was just 14 years old.

The discovery is a much-needed windfall for Whiting, who has been unable to work since 2003 due to disability. Comparable ultra-rare photos of legendary American outlaws have sold for millions of dollars.

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Thought to be a copy, this elegant marble bust sat largely ignored in the main meeting room of the borough hall of Madison, New Jersey for 80 years. In 2014, art student Mallory Mortillaro was appointed to carry out an inventory of the hall's artworks, and made a beeline for the sculpture.

The eagle-eyed rookie archivist examined the bust and discovered a signature that read 'A Rodin' in the sculptor's inimitable style – why nobody else had noticed it before is anyone's guess. Intrigued, Mortillaro approached the Comité Auguste Rodin in Paris, the world-renowned authority on the artist.

The Comité unearthed a photo of Rodin himself posing with the sculpture, which is a bust of Napoleon. Now worth up to $12 million (£9.1m), the piece was donated to the hall by heiress Geraldine Rockefeller Dodge during the 1930s and its real provenance had been forgotten over time.

This portrait, which was assumed to have been painted by an unknown in the style of great Renaissance master Raphael, languished in the basement of an Italian palazzo for 40 years until April 2010. Art expert Mario Scalini came across it that year while he was sorting through the vaults.

Scalini was immediately drawn to the ornate frame, and questioned why a seemingly worthless artwork would have been framed so lavishly. On closer inspection, the art pro realised he was looking at a lost Raphael painting.

The picture, which is owned by a public art gallery in Modena, was sent off for analysis using the latest infrared and UV multilayer technology and was confirmed, beyond reasonable doubt, to be a genuine Raphael worth up to a whopping $34 million (£25.6m).

When Edna, Lady Samuel of Wych Cross, bequeathed this painting to the UK's National Trust charity in 2010, most experts had dismissed it as an inferior work painted by a student or imitator of Dutch master Rembrandt van Rijn.

The painting was acquired by Lady Samuel's husband in the 1960s. After the experts of time doubted its authenticity, the artwork was placed in storage at Buckland Abbey in Devon and left to gather dust until it was 'rediscovered' in 2005 by Rembrandt expert Ernst van de Wetering.

Van de Wetering was sure the painting was a genuine Rembrandt but it wasn't until 2013 that he was able to prove it is actually the Dutch master's first 'selfie', painted when the artist was 29 years old. The artwork is estimated to be worth in the region of $26.4 million (£20m).

Norwegian industrialist Christian Nicolai Mustad bought this Van Gogh painting in 1908 and proudly displayed the artwork until the French ambassador to Sweden told him it was an amateurish fake. Horrified and embarrassed, Mustad banished the painting to an attic.

Following Mustad's death in 1970, the painting was reappraised but still deemed to be a copy. Further investigations by Amsterdam's Van Gogh Museum in 1991 proved just as fruitless. In 2011, the museum opted to study the painting one last time.

Employing the latest X-ray technology and a slew of other advanced methods, experts revealed the picture was painted by Van Gogh during his stay in the south of France, around 1888. The property of one of Mustad's heirs, it is now worth upwards of $50 million (£38m).

In 2012, three oil paintings long presumed to be fakes were confirmed as genuine artworks by one of Britain's most important artists, JMW Turner. The canvases were donated to the National Museum Cardiff by collectors Gwendoline and Margaret Davies in 1956.

The trio of works were rejected by experts who deemed them inferior paintings by students of Turner. The BBC's Fake or Fortune? show got on the case and arranged for the canvases to be re-evaluated using modern technology.

The advanced X-ray, infrared and pigment tests showed the paintings are most definitely the work of Turner, much to the delight of the museum's curators. Together, the trio could be worth up $80 million (£61.3m) on the open market.

Another masterpiece authenticated thanks to cutting-edge technology, this painting of a haystack was revealed to be a true Claude Monet work in 2015. The painting had been purchased in the 1950s from a London dealer by Finland's Gösta Serlachius Fine Arts Foundation.

The painting was thought to have been produced by Monet, but it lacked a visible signature and experts were unable to find any reference to it. Some experts believed the picture was painted by an unknown in the style of the Impressionist artist.

Researchers at the University of Jyväskylä used a hyperspectral camera to pinpoint the signature and date of the artwork, and studied the fibres and paint to conclude the artwork is indeed a Monet. A similar painting from the artist's haystack series realised $81.4 million (£61.8m) at auction in 2016.

This painting of Christ as Salvator Mundi was thought to be a heavily overpainted copy of a lost original by Leonardo da Vinci. It was acquired in 2005 at a New Orleans auction for just $10,000 (£7,590) by a consortium of art experts who believed it could be an authentic work by the genius artist.

The consortium, which included Old Masters expert Robert Simon, had the painting restored by New York University's Dianne Dwyer Modestini, and it was eventually attributed to Da Vinci. The restored painting was unveiled at an exhibition at London's National Gallery in 2011.

Yves Bouvier, a Swiss dealer, bagged the painting in 2013 for $75 million (£56.9m) and sold it on to Russian oligarch Dmitry Rybolovlev, who paid $127.5 million (£96.7m) for it. In November 2017, Salvator Mundi was acquired by Saudi's Crown Prince Mohammed bin Salman for $450.3 million (£341.6m), a new world record price for an artwork.

Found in a Nazi art hoard of 1,500 pieces in the Museum of Fine Art in Bern, Switzerland the origins of this watercolour sketch were dubious. However, BBC show Fake or Fortune? has worked out that the sketch is a genuine Henry Moore work and worth $92,000 (£70k).

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The museum had acquired the sketch in 2014 after its owner Cornelius Gurlitt died. Some of his collection had controversial origins, having been stolen by the Nazis and the result of forced sales by Jewish collectors. However, the investigation surrounding this sketch by Moore found that it was given by the 20th-century artist to a German museum, and had been bought by Gurlitt's father before the war.

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The Madonna of the Pomegranate painting by Sandro Botticelli dates back to the 15th century. But when English Heritage were restoring what was first thought to be a later copy by an unknown artist, restorers soon realised that the similarities were just too close. After speaking with experts from the National Gallery and the Victoria and Albert Museum the discovery was confirmed.

The size compared to the original painting in Florence, as well as discolouring, led experts to believe it was fake at first until X-ray and pigment analysis were able to determine that it did come from Botticelli's Florence workshop. It is thought to be one of many paintings recommissioned by the artist, and it is now believed to be the closest version to the original piece. Madonna of the Pomegranate is on display at English Heritage’s Ranger's House in Greenwich, London.

A rare Anglo-Saxon coin has been discovered and declared a treasure, despite the fact that it is actually a counterfeit. The reason why it is still technically classed as treasure is because it was discovered to have been made between the years 630 and 650, meaning that the coin is a rare counterfeit of its time.

The coin, which was found in Woodbridge, Suffolk in 2016, is an unofficial 7th-century copy and has spelling mistakes and dents in the material on both sides. It's these signs that make experts assume that the coin was a counterfeit blunder of its time. Therefore, it is still classed as rare and from the Anglo-Saxon period, making this a unique piece of treasure.

A painting purchased by Queen Victoria in the 19th century turned out to be an original piece by artist Lucas Cranach the Elder, a famous court artist, from the 16th century. The painting, which Queen Victoria bought to give to her husband Prince Albert in 1840, was thought to be a fake for more than a century.

The painting, which has been cleaned and restored, is titled: Portrait of a Lady and Her Son. It was painted between 1510 and 1540. It depicts Lady Sybilla of Saxony and her son. The painting was X-rayed and examined before a final conclusion about its authenticity was made. The current record for a Cranach the Elder painting is $12.1 million (£9.3m). 

A gem which was thought to be costume jewellery has in fact been identified as a real 19th-century 26.27 carat diamond. The stone actually cost only £10 when it was bought in London, and it was only after it was valued that its true worth was discovered. 

Nicknamed the "tenner" diamond, due to the price it was purchased for at a flea market some 30 years ago, it sold for a whopping $865,600 (£656,750) at auction in 2017. Diamonds from the 19th century were not typically cut to show their clarity, which explains why the precious stone went undetected for so long as it would not have resembled modern diamonds.

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In 2017 a rare gold coin was discovered in a farmer’s field in Dorset. The coin features an image of the archangel Michael slaying a dragon, hence its nickname 'The Angel Gold Coin'. While at first it was thought to be a bottle top, it was then identified as an original 15th-century coin and estimated to be worth a huge $19,780 (£15,000). However, the coin actually went on to sell for as much as $65,900 (£50,000) at auction.

The coin is believed to have stopped being minted during the 86-day reign of 12-year-old King Edward V, after he vanished in the Tower of London along with his brother in 1483. This means that the coin had been buried in the field undisturbed for over 500 years before it was discovered. The text on the edges of the coin reads: ‘Edward Di Gra’ which, experts say, conclusively shows the coin was made during the short-lived reign of Edward V.

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